The foliage of palms and other broadleaf evergreen ornamentals can be damaged or killed during winter by a combination of cold temperatures and wind stress. Heavy mulching reduces temperature stress to roots and lower parts of the plant shoot tissues and is an effective way to protect marginal ornamentals from winter cold (reviewed in Francko 2003). However, winter winds tend to blow this protective mulch layer away. Further, mulching cannot protect plant tissues above the mulch line that are exposed to the environment.
In addition, palms and many ornamentals are susceptible to late winter/early spring mortality caused by bud/crown rot disease. Winter precipitation collects in the open crown cavities of these species, freezing and thawing and resulting in mechanical damage to tender bud tissue. This damage creates ideal growing conditions for opportunistic fungal and bacterial pathogens. In susceptible species exposed to sub-lethal cold, the majority of spear leaves are destroyed by this disease, and, left untreated, this disease can kill all the viable bud tissue and thus the entire plant (reviewed in SPEPS 1994 and Francko 2003).
There remains a need in the art for ways to ameliorate temperature and wind stress to plants. Additionally, there remains a need in the art for ways to exclude atmospheric precipitation and frost deposition from the crown cavity of palms, ornamentals, and other plants.